Bicyclic lactams



Lac-

United States Patent BICYCLIC LACTAMS John Clark Sheehan, Arlington,Mass., assignor to Bristol Laboratories Inc., Syracuse, N. Y., acorporation of New York No Drawing. Application January 5, 1953, SerialNo. 329,731

16 Claims. (Cl. 260239.1)

This invention relates to compounds having bacteriostatic, bacteriocidaland fungistatic properties and the methods of their preparation. Some ofthese compounds are useful in the synthesis of penicillin. Moreparticularly, this invention relates to new methods for the preparationof compounds containing the basic fused fi-lactam-thiazolidine ringspresent in the fi-lactam structure for penicillin. The compounds of thepresent invention are also useful as chemical intermediates fortransformation into aminoand substituted-amino-Z- thiazolidine-aceticacid S-lactams having bacteriostatic properties and substituents asindicated. This transformation is effected by rupture of one or twobonds between the carbonyl atoms and the exocyclic nitrogen atom,followed, if desired, by acylation, as with phenylacetic acid chloride.Compounds have been synthesized in which the combination of this ringsystem with an acylamino function alpha to the lactam carbonyl has beenachieved for the first time. A striking feature of the present inventionis that a compound has been prepared by a synthesis specificallydesigned to yield a ,B-lactam, which undergoes two typical and importantpenicillin reactions and possesses an infrared spectrum in the criticalrange almost identical to that of penicillin. This invention, therefore,constitutes the first chemical evidence from the synthetic side, for thefi-lactam formulation of penicillin.

This application is a continuation-in-part of my prior, co-pendingapplication, Serial No. 176,013 filed July 26, 1950, and now abandoned.

Very limited success has heretofore been attained in the synthesis offused ,3-lactam-thiazolidine systems. The present invention represents aconsiderable advance in that this fused ring system in conjunction withthe a-acylamine function has been attained, and for the first time sucha synthetic structure has been shown to gundergo chemical reactionstypical to penicillin itself.

An extension of this reaction to the preparation of bicyclic B-lactamsby the action of an acid chloride on a thiazoline (a cyclic imine) hasresulted in the preparation of three fused ,B-lactams, all conforming toStructure I.

In only one case has a ketene been added directly to a thiazoline toform a B-lactam. Diphenyl ketene reacts with Z-phenyl-Z-thiazoline (H)to give the B-lactam of 2,,m-triphenyl-Z-thiazolidineacetic acid (Ia,R1=R2=Rs=CsH5) Dimethyl ketene reacts with 2-methyl-2-thiazoline and2-phenyl-2-thiazoline to give the corresponding piperidinediones (seeIII), which are convertible to the fl-lactams by partial hydrolysisfollowed by pyrolysis.

" ice A large number of attempts have been made to synthesizepenicillin-like structures, including the attempted reaction of keteneswith a variety of thiazolines. Much effort has been expended in attemptsto add ketene itself to thiazolines. Several attempts made by differentinvestigators led to no crystalline product and no other evidence offi-lactam formation.

There is now discovered according to the present invention a compound ofthe general formula RaCCH Efff Hill-0:0

wherein R1 represents a member selected from the group consisting ofphthalimido, 3.-nitrophthalimi do, succinimido, anddi(methaneslllfonyl)amino; R2 represents a member selected from thegroup consisting of hydrogen and phenyl; R3 and R4 each represents amember selected from the group consisting of lower alkyl and hydrogenand R3 and R4 are alike; and R5 represents a member selected from thegroup consisting of hydrogen, carboxy and (lower)carbalkoxy.

The important results to be described are summarized in the followingequations and discussion.

EQUATION 1 Percent 32 5 Negligble. 45%

EQUATION 2 CHz-C CHr-CH: l

XII

Phthalylglycyl chloride, triethylamine and 2-ph'enyl-2- thiazoline, inbenzene solution, reacted to form the bicyclic lactam. The mostsuccessful application of this reaction depends upon the employment ofthe proper experimental conditions, especially the degree of dilu tionand order of addition of the reagents. A benzene solution of the acidchloride (one mole) was added, in a relatively short period of time, toa benzene solution of the imine (one and one-half r'n'ole's) andtriethylamine (one mole). There was formed an essentially quantitativeyield of triethylammonium chloride, and approximately 45% of the keteneresidue as a benzene insoluble product formed from three moles of theketene and one of the thiazoline, whose analysis corresponded tostructure V, of Equation 1. From the henzene filtrate the fl-lactam wasisolated along with 61% of unreacted thiazoline.

A high dilution technique was employed fo'r optimum results [Cope, J.Amer. Chem. Soc., 72, 983 (1950)]. A solution of 2-phenyl-2-thiazolineand phthalylglycyl chloride in ether was prepared. The ether wasmaintained at rapid reflux and a solution of triethylamine in ether wasadded over an extended period (four hours) in such a way that each dropof solution was mixed with a large volume of returning ether condensateand thus entered the reaction flask in a highly diluted state. Thethiazoline was therefore always in great excess with respect to the acidchloride. By this procedure, a good (31.5%) yield of the purifiedfl-lactam (IV) was obtained. The theoretical amount of amine salt wasisolated, but the amount of (V) formed was negligible. Recrystallizationfrom aqueous-acetone and ethanol gave the pure fl-lactatn (M. P.215-2165). 1

The present application of the high dilution technique,

( s)2(I3CHCOiCH:

providing for a dimolecular at the expense of a termolecular reaction(and involving two difierent compounds) is a unique departure from theconventional use of the method, in which intramolecular reaction isfavored over polymerization. I

Evidenced for the'struc'ture of the fi-lac'tam (IV) was obtained byoxidation to the corresponding sulfone (VIII). The action of potassiumpermanganate of the lactam (IV) in dioxanezacetic acidzwater (10:3;1)afiio'r'ded the sulfone (VIII) in 59% yield obtained as colorless cubiccrystals, melting at 225. One of the strong arguments supporting theB-lactam structure of penicillin is the oxidation of methylbenzylpenicillinate to the 'sulfone. It is known thatN-acylthiazolidines give sulfones on oxidation, although thecorresponding thiazolidines without an N-acyl group on similar oxidationgive products which result from cleavage of the thiazolidine ring. Otherwork, such as the oxidation of dimethyl N-benzoy1-D,L-benzy1penicilloateto the corresponding sulfone, in addition to older evidence of theinherent instability of the D-u-ainino sulfone structure, warranted theformulation of penicillin as an N-acylated thiazol-idine.

The present invention is the first instance of the formation of asulfone from a synthetic fused B-lactam-thiazolidine compound. Attemptsto so oxidize two of the lactams obtained by the Shell group failed.

Alkaline hydrolysis of the lactam (IV) by treatment with one moleofdilute sodium hydroxide for twenty minutes gaveZ-phenyl-a-(o-carboxybenzamide) 2 thiazolidineacetic acid ,s-lactam in75% yield, obtained as fine needles melting at l37.5*l39.5 '(dec.).Since the susceptibility of this B-lactam linkage to hydrolysis wasunknown there was some doubt as to whether the lactam bond or thephthalimide group had been opened. It is known that the phthalyl groupis extremely sensitive to alkali. Proof that the phthalyl group was thepoint of attack was provided by the successful reclo'sure of the acid tothe original lac tam (IV) by use of acetic anhydride. The easyelimination of water by such o=carboxybenz'amides, even by simplyheating above the melting point is well-known. Moreover, many attemptsduring the penicillin synthesis program to reactivate it-penicilloatesusing a wide variety of dehydrating agents, including acetic anhydride,all failed.

The acid (VI) was converted to its methyl ester (VII), (M. P. 148-l49),in 54% yield by the use of diaz omethane. This compound and its parentacid are the 7 closest synthetic analogues of penicillin thus farreported. The corresponding S-nitrQphthalimido-B-Iactam was synthesized(Equation 2). The comparative method was similar to that used for theunsubstituted lactam. The yield was 17% as colorless rectangular prisms,melting at 210211 (dec.).

Determination of the infrared spectrum of the lactam methyl ester (VII,Figure 1 of the attached drawings) together with that of the parentlactam (IV, Figure 2) and a comparison of these with the spectrum ofmethyl benzylpenicillinate (Figure 3) provides strong proof of the closestructural similarity of the ester (VII) with penicillin. V

Penicillin shows a strong band at 1780 cmr This was early assigned tothe lactam carbonyl on the basis of theoretical arguments. The lactamcarbonyl is shifted in monocyclic lactams to the value of 1740 cmf achange indicative of greater double-bond character of the C=O bond as aresult of the dampening of normal amide resonanceby the four-memberedring. Since X-ray crystallography of penicillin has confirmed that thetwo fused rings are not coplanar the probability of amide resonance tothe dipolar form is even less in the bicyclic lactam. It isnot'surprising therefore to find the lactam carbonyl in penicillinabsorbing at 1780 cmr close to the range of the pure carbonyl group.Later, when the spectra of the synthetic ,B-lactams were determined,they also were found to show strong bands at this same value. In ourdetermination of methyl benzylpenicillinate, the lactam carbonyl absorbsat 1785 GEL-1; the lactam carbonyl band of the synthetic compound is at1777 cm.- The carbomethoxyl group in penicillin absorbs at 1748 cm. we

assign the band at 1724 cm." of the synthetic sample to thecarbomethoxyl. In penicillin the bands at 1677 and 1507 cmr areattributed to the monosubstituted amide group; the'synthetic compoundabsorbs at 1678 and 1507 cmr and we assign these bands also to themonosubsti tuted amide group. Both curves show weak bands at 1600 cm."and these are attributed to the phenyl groups.

The infrared spectrum of the phthalimide lactam (IV) discloses abroadband at 1784. cmr The spectrum of N,N-diethyl phthalylglycyl amide showsthat it possesses a band at 1725 cm. and a strong, but narrow,

'band at 1776 cmr' both of which we assign to the teristic ofmonosubstituted amides and does not appear until the'compound isesterified.

The following examples will better serve to illustrate the inventionwithout limiting it thereto. All temperatures in this application are indegrees centigrade.

Example I 2-phefzyl-o-phthalimido-Z-thiazolidineacetic acid S-Zactam(IV)-high dilution A solution of 4.48 g. (0.0200 mole) of phthalylglycylchloride and 3.36 g. (0.0200 mole) of 2-phenyl-2-thiazoline in 75 ml. ofether was placed in a 200 ml. threeneck flask bearing a mercury-sealstirrer and a small The,

high-dilution addition tube (which carried, in turn, an

V efficient reflux condenser and a dropping funnel). Some flocculentWhite precipitate was formed, probably a result of slightly impurereactants, and represented only a small a 7 portion of the materials.

V ml; of ether was then added over a four hour period.

The solid was collected by filtration onto a small, tared Biichnerfunnel, washed with ether, dried at 70 and weighed, then washed withwater, redried'at 70 and weighed. The loss in weight was 2.54 g.,equivalent to 93% of the theoretical yield of amine hydrochloride. Theresidue weighed 5.64 g., tan solid M. P. 160-195". The ether solutionwas concentrated to dryness to give a small amount. of oily materialwhich resembled the starting thiazoline. r

The main reaction residue was digested with 2 x 20 ml,

portions of ether, which removed some oily material but not much color.The residue was then digested with ml. of boiling ethanol (95 andfiltered hot.. The residue was the lactam (IV); Weight 2.20 g. (31.5%),white powder, M. P. 203-213. This material was sufliciently pure for usein subsequent preparations. The

impurities to be removed were absorbed thiazoline and (Jalculated FoundC 65. 65. 07 H 4. 03 4. 12 N 8. 00 7. S 9. 15 9. 14

The lactam (IV) is insoluble in water; moderately soluble in acetone,ethanol and benzene; somewhat more soluble in dioxane. V and does notreact with mercuric chloride in ethanolether.

Oth er c0nditi0ns.-In a run involving direct mixing of the threereactants 1.0 g. (0.00614 mole) of the phenyl thiazoline (II) and 1.375g. (00.00614 mole) of phthalylglycyl chloride were mixed in a test-tube.Warming to 70 gave a clear solution. Triethylamine, 0.85 ml. (0.62 g.,0.00614-mole) was then added and there was an immediate, vigorousreaction during which the mixture changed to yellow gelatinous paste.After thorough stirring the mixture was diluted with 20 ml. of benzeneand filtered. The solid was washed with benzene, dried, washed withwater and again dried. The loss in weight was equivalent to 96% of aquantitative yield of amine hydrochloride. The residue weighed 0.69 g.

Concentration of the benzene filtrate under reduced pressure afiorded anorange syrup which was'triturated with acetone to yield a small crop ofcrystals. Collection and washing with acetone yielded the. lactam (IV);weight 0.24 g. (11%); M. P. 208-211" (s. 206).

A 'double high dilution run gave good results. The thiazoline, in ethersolution, was placed in the reaction fiask and other solutions of theamine and acid chloride were added simultaneously through separateaddition tubes. The yield was 27%"of the lactam (IV).

EXAMPLE II Sulfone of Z-phenyI-m-phthdlimid0-2-thiazolidine-acetic.

acid fl-lactam (VIII) A solution of potassium permanganate (0.34 g.) ina mixture of 10 ml. of glacial acetic acid and 3 ml. of water was addedto a solution of 0.28 g. (0.0080 mole) of the phthalimidolactam (IV) in30 ml. of purified dioxane. The mixture was kept at room temperature forone hour with occasional shaking, during which. time the permanganatecolor gradually gave way to a brown precipitate. Sulfu rous acid (6%solution) was then added until It gives a negative sulfhydryl testCalculated 3 Found C 59. 67 59. 66 Fr 3. 69 3. 71 N 7.34 7. a5

EXAMPLE III a-(a-Carboxybenzamide)-2-phenyl-2-thiaz0lidine acetic acid,B-lactam (VI) A solution of 0.350 g. (0.00100 mole) of thephthalimidolactam (IV) in ml. of warm dioxane was carefully cooled toroom temperature and 10.4 ml. of 0.0970 N sodium hydroxide (0.00100mole) solution added. A yellow color developed immediately and a lightflocculent precipitate formed. The pH was approximately 8 after oneminute, 6 after ten minutes, and appeared to be constant at 6 aftertwenty minutes. Filtration and addition of 10 ml. of 0.10 N hydrochloricacid caused disappearance of the yellow color and formation of a whiteprecipitate. The mixture was diluted with 20 ml. of water and after tenminutes the solid was collected by filtration and air-dried; yield 0.27g. (74%); M. P. 1315-1335 (dec., s. 130); negative sulfhydryl test.Recrystallization by dissolving 0.100 g. in a mixture of 4 ml. ofacetone-dioxane (3:1) and adding 3 ml. of water afforded the lactam-acid(VI) as fine, colorless needles; Weight, 0.075 g.; M. P. 1375-1395 (to ared liquid). A second recrystallization gave essentially the samemelting point which appeared to depend somewhat upon the rate ofheating.

Analysis-Calculated for C19H16N2SO4:

melted at 141-142" (dec.).

Recloszzre of the phthalimide ring with acetic anhydride. Preparation ofthe phthalimidolactam (IV) from the lactanz-acid (VI) Twenty-fivemilligrams of the lactam acid (VI) was boiled for ten minutes (boilingfor one minute was found to be inadequate) with 0.25 ml. of aceticanhydride. After cooling to room temperature the excess anhydride wasdecomposed by shaking with 1 ml. of water. A white crystallineprecipitate was separated by centrifugation, and decantation of theliquor. The residue was recrystallized by dissolving in 0.25 ml. ofacetone and adding 0.5 ml. of water, to afford a crop of needle-shapedcrystals; M. P. 210-213 (dec., evolution of gas). The melting point of amixture with an authentic sample of the phthalimidolactam (IV) (M. P.213.5215) was 212-215 EXAMIPLE IV a-(O-CarbOmethom)-2-phenyl-2thiazolidine acetic acid fi-lactam (VII) Two milliliters ofan 0.7 N ethereal diazomethane solution was added to 0.10 g. of thelactam-acid (VI) 10 suspended in a mixture of 5 ml. of ether and 5 m1.of chloroform. The solid immediately dissolved and gas was evolved.Evaporation of the solvent under reduced pressure afforded a whiteflulfy powder. This was leached with 15 ml. of anhydrous ether and theether solution filtered to remove some insoluble material (approximately30%). Concentration of the filtrate to 5 ml. and addition of 5 ml. ofpentane afforded the product; yield 0.055 g. (53%); M. P. 141-1425".Recrystallization by dissolving in a mixture of 1 ml. of ether and 2 ml.of chloroform followed by dilution with 4 ml. of pentane yielded theester (VII) as fine, colorless, rectangular prisms; weight 0.030 g.; M.P. 148149 (s. 147) (depressed on admixture with the acid (VI)Analysis.Calculated for C2oH1aN2O4S (382.4):

Calculated Found EXAMPLE V A three-neck, 200 ml. flask was fitted with amercuryseal stirrer, (XIII) a stopper bearing a thermometer, and ahigh-dilution addition tube. In the flask was placed a solution of 2.67g. (0.0100 mole) of 3-nitrophthalylglycyl chloride (XII) in 60 ml. ofdry benzene and 40 m1. of dry ether (the low solubility of the chloridenecessitated the use of benzene). 2-phenyl-2-thia'zoli'ne (1.63 g.;0.0100 mole) was then added. The stirrer was started and heating begununtil there was a rapid stream of con densate back through the additiontube. A solution of 1.40 ml. (1.01 g., 0.0100 mole) of triethylamine in40 ml. of ether was added in the course of forty-five minutes. Thethermometer read 62 at the start and 58 at the end. The mixture wasstirred for fifteen minutes at reflux temperature and then forforty-five minutes While cooling to room temperature. The solid productwas then filtered, washed with ether, and dried, leached with water,filtered, spread on a dish and air-dried. The toss in weight was 1.18g., equivalent to 86% of the theoretical yield of triethylammoniumchloride. The residue weighed 1.04 g., M. P. -220.

The product (XIII) was recovered from the benzeneether filtrate. Afterstanding this deposited a crop of solid which was recrystallized from 60ml. of 1:1 acetonepentane to give 0.19 g. of material of melting point182-200. The benzene-ether solution which had been decanted off wasdiluted with ether until precipitation was complete. The precipitate wasa yellow orange gum. After removing the supernatant liquor the gum waswashed with a little acetone to absorb most of the color. The liquorswere combined. On boiling the residue with 10 ml. of acetone only a partwas dissolved and a white residue remained. The acetone was decanted and10 ml. of pentane added to precipitate a yellow crop which was filteredofi. The weight was 0.32 g.; M. P. 203206 (dec., s. The residue from theacetone treatment was dissolved in 30 ml. of acetone and 30 ml. of wateradded to precipitate a crop of fine rectangular prisms (the nitrolactam(XIII); weight 0.060 g.; M. P. 210211 (evolution of gas and charting).Recrystallization from aqueous acetone did not change the melting point.

Analysis.Calculated for C19H13N3O5S (394.5):

Calculated Found 11 The yield of pure and semi-pure material was thus0.06+0.32 g.=0.38 g.

The 1.04 g. of insoluble residue from the main reaction mixture isconsidered to be 3-nitrophthalylglycylanhy- CHz-CO CsH: 80:

of- 35% hydrogen peroxide. The white, somewhat cloudy suspension wasfurther diluted with 15 ml. of water, thesulfone floating to the surfaceas a fleecy mass. Under the microscope the material was highlycrystalline.

dride. Solution of 0.200 g. of this product is 12 ml. of It was filteredofi, washed with water, and dried in vacuo; acetone, followed byaddition of 12 ml. of pentane, proyield, 100 mg. (93%), M. P. 243244'duced a yellow powder; weight 0.10 g.; M. P. 220-225 The above crudeproduct was dissolved in a mixture (dec., evolution of gas, 5.210").This solution in 12 ml. of 5 ml. of methanol and 5 ml. of acetone bywarming. of acetone and addition of ml. of pentane aiforded a Afterfiltering from a slight cloudiness, 2 ml. of water crop of colorless,rectangular prisms; weight 0.500 g.; was added. On cooling, flat platesprecipitated from the M. P. 237238 (evolution of gas, s. 236). solution;yield, 65 mg., M. P. 251254. The mother- Analysis.-Calculated forC20H10N4O11 (482.3): liquor yielded a further mg. of product, M. P.

'- 251-254; (combined yield, 80 mg. (75%)).

Calculated Found Analysis.Calculated for C23H20N2O7S:

49.80 40.99 0.1mm meat 2. 09 2. 04 a 11.61 11.

4.30 4.39 EXAMPLE VT v N. u. 5.98 1 5.90 4-thia-1-azabicyclo3,2,0-2-hepzanecarb0xylic acid, 3,3-di- S 1 70 methyl 7 0x0 5 phenyl 6phthalimid0-,methyl ester (XV) EXAMPLE VIII In a 200 ml. three-neckedflask was placed 2.39 g. (0.01174'dlphenyl'3-(NZ'.dlmethil;;?lf0nylamln0)2- mole) of methyl5,S-dirnethyl-2-phenyl-2-thiazoline-4 carboxylate in 50 ml. of dry etherand 2.24 g. 0.01 mole) To a PP 8011mm of a (09166 mole) i ofphthalimido-acetyl chloride in 50 ml. of dry ether was benlalagllm? and(o-slgw 000800 mole) f added through a Ziegler high-dilution cycle overa period ethylamme 15 mL of benzene was added dropwlse a of two hourssolution of 2.00 g. (0.00800 mole) of dimethanesulfonyl- The reactionmixture was filtered from the precipitate, amlqoacetyl chlorifle in 50benZeQefthe addition and the ether filtrate was concentrated to about 25ml. requlred twenty mmutes)- A Whlt? Preclpltate to and 'again filteredfrom the precipitate. On standing form "i 911cc and at the end themixture? was so vlscous overnight, this ether filtrate deposited blunt,colorless f stlrnflg had to done manually Wlth a heavy needles whichwere covered with a yellow, Somewhat TlllS stirring was continuedintermittently for thirty mingummy (The mothepliquor, on addition f utesand the insoluble material was then filtered off onto picric acid,yielded picrat f some of the unreacted a small, tared Biichner funnel,washed with benzene and starting thiazoline, M. P. 105-106"). The abovecrude dried at The dry Product was Washed y slllffying product, theyellow, gummy powder, Weighed 220 mg with water, refiltered and redried.The loss in weight M. P. ca. 190. It was recrystallized from anacetonewas L05 o equivalent to 96% 0f the theoretical Yield of ligroinmixture; P. 40 amine hydrochloride. The residue weighed 1.56 g.; M. P.

Analysis calculated for CHHZONZOSS: l87200 (dec.), negative chlorinetest (Beilsteins copper wire). This residue was dissolved in 70 ml. ofboiling calculated Found acetone and filtered to remove 0.3 g. ofinsoluble material, which was not investigated. Addition of 20 ml. ofwater 0 63 29 6335 afforded colorless crystals; weight 0.77 g.; M. P.HZIIIII:I:I:I:I::::::::::::: 4:62 4.74 235236.5 (dec., sintering at233). By concentration 44 of the main benzene filtrate to 5 ml. ofseeding, additional product was obtained (colorless needles); weight0.45 g.; 7 EXAMPLE VII M. P. 235236.5. The total yield was 1.22 g.(39%). 4-thz'a-1-azabicyclo 3,2,0-2-heptanecarb0xylic acid, 3,3-Recrystallization of 0.45 g. from 40 ml. of acetone and 20dimethyl-7-0xo-5-phenyl-6-phthalimid0-,methyl ester, ml. of water gavethe product as fine needles; weight'0.40 4-di0xide (XVI) g., M. P.235.5-2365" (no dec.). 100 mg. of the preceding compound wa dissglvedAnalysis.Calculated for C17H1sNzOsSz (394.4): with warming in 6 ml. of80% acetic acid. With warming, 250 mg. of potassium permanganate wasdissolved in Calculated Found 3 ml. of water. The solution of compoundin acetic acid was added to the permanganate solution, and the reaction.9, mixture was allowed to stand for twenty minutes. The N 7111 7:07reaction mixture was then decolorized with several drops V EQUATION 6CHz-CH2 CO CO S CH:-CO CaHs S otm t vm (@N (3H1 1 1CHO om (13H: NCH: C OC O,l ICH2 oool XVIII XIX XX on. N-CH-l? on: i CH: 00 C0-NCH: oo-rr--dni xxn XXI EQUATION 7 of the primary amide falls at 6.6 as inpenicillin, rather CuHSCOzH Pisa than at the lower wavelength usuallyobserved with pri- OH NE OH NH mary amides (near 6.511.).

' ea The preparation of a similar .series of compounds 0006115 5 whichpossess the 5,5-geminal dimethyl grouping char- XXIII XXIV acteristic ofpenicillin was also carired out. Condensation of benzoic acid andisobutanolamine (XXIII) 0511 S R CBH5 S a nomoooi yielded the amide XXIVin 76% yield, which was (if (Imam), -Y (HEP-C C(CHK)? cyclized byreaction with phosphorus pentasulfide to N -on. (JO-N on. yield 41% ofthe thiazoline XXV. The reaction of XXV XXVI, R=succmimide XXV withsuccinimidoacetyl chloride and triethylamine V R=phth81imide 16% of thedesired lactam XXVI. A similar reaction EQUATION 8 i f (can) N 3H: cstem), -5 COO] N-CHCO:C a

XXVIII Asulfone (XXX) KMnOt/ R 0&5 S (1) H0 HsCOzCCHzCHzCONH oaHs S on-oowm on-o C(CH3):

I l (2) CHQNQ CO-N CHCOQCHS CO-N 0110010113 XXIX XXXI t I ]THHCsHs(NO2)zn y S rage 015E158 CHzNHCOOHzCHzCOzH ctnscnzcorrn /S\ XXXII CH-CH'C(CH:|)2 R=succinimido XXXIII I CO-N CHCOzCH:

Methyl benzylpeuicillinate (penicillin G Methyl ester) The simplestlactam (XX) prepared in this work was obtained by interaction of2-phenyl-2-thiazoline (XIX) and succinimidoacetyl chloride (XVIII). Thereaction showed even greater sensitivity to conditions than theanalogous procedure in the case of phthaloylglycyl chloride, and thestandard method previously used (high dilution addition of triethylaminein ether to a mixture or" thiazoline and acid chloride in refluxingether) yielded no isolable lactam. A similar procedure using refluxingbenzene resulted in a 14% yield of the adduct XX, but the isolation wasvery difiicult. The most successful preparation, involving the use ofmethylene chloride as a solvent under high dilution conditions, yielded56% of the desired lactam XX directly in easily purified state from thecrude reaction mixture. The use of the latter procedure has provedsuccessful repeatedly in the similar preparations to be described,several of which failed to yield appreciable amounts of lactam whencarried out in other solvents.

The structure of the lactam XX was readily assigned on the basis ofoxidation to the sulfone XXII and infrared spectrum.

The spectrum of XX shows the characteristic strong band at 5.6 .5 due toB-lactam carbonyl stretching in addition to the succinimido carbonylband at 5.8,. The characteristically very weak band of the succinimidogroups at 5.6a coincides with the S-lactam band.

The oxidation of the lactam XX to the corresponding sulfone XXII inquantitative yield using potassium permanganate in aceticacid-dioxane-water was carried out under conditions known to lead tohigh yields of the sulfone of methyl benzylpencillinate.

Hydrolysis of the succinimido protecting group proceeded readily on slowtitration of a dioxane solution with 0.1 N base. The correspondingmethyl ester )OCI was prepared, using diazomethane, in 67% overallyield. The infrared spectrum of this lactam shows clearly thecharacteristic lactam band at 5.65m, primary amide bands at 2.92;.t, 593and 6.6011. and the estercarbonyl at 5.80;!" It is interesting to notethat the high wavelength band with phthalimidoacetyl chloride in etheryielded the corresponding phthalimido lactam XXVlI in only 5% yield.

Starting material for the preparation of members of thefl-lactam-thiazolidine series related to 5-phenylpenicillin itself wasmethyl 2phenyl-5,5-dimethyl-2 thiazoline-4-carboxylate (XXVIII),obtained from natural penicillamine by esterification followed by ringformation with ethyl-benzimidate. Under the conditions of thisparticular preparation, which involved evaporative distillation at 150,the product was apparently completely recemized. Reaction of thethiazoline XXVIII with succinimidoacetyl chloride under high-dilutionconditions yielded 13% of the desired lactam XXIX, which was readilyoxidized to the sulfone XXX in 76% yield. The infrared spectrum of XXIXshows the characteristic ester band at 5.7g in addition to the expected5.6 lactam and 5.8;1. succinimido bands. Alkaline degradation of XXIXled to N-phenylsuccinamic acid, isolated as the2,4-dinitrophenylhydrazone.

Hydrolysis and esterification of XXIX affords a 29% yield of thecorresponding a-acylamino derivatives XXXI, which has an infraredspectrum similar to that of natural methyl henzylpenicillinate itself(XXXIII). Disappearance of the strong 5.8 band of the succinimido groupreveals the 5.8 ester which is thus shown to be due to the side-chaincarbomethoxy group. Compound XXXI, methyl 5-phenyl-fi-carbomethoxyethylpenicillinate, is a synthetic analog of penicillin.

EXAMPLE IX Succz'nimidoacetic acid.A well pulverized mixture of succinicanhydride (50.0 g., 0.5 mole) and glycine (37.6 g., 0.5 mole) wasevacuated to 0.5 mm. and then heated in an oil bath at After warmingslowly to the mixture was maintained at for two hours. On cooling, themelt solidified to a brown cake, which was dissolved in 200 ml. ofboiling ethyl acetate and decolorized with Norit. The crude productseparated at 50.4 g. (60%) of colorless needles, M. P. 105-116".

r (92%), M. P. 6880.

' This product gave the same results in the preparation of XVIII as aportion recrystallized from ethyl acetate, M. P. 117 120. ScheiberandBeckleben report the melting point at 113.

EXAMPLE X Succinimidoacetyl chloride A mixture of succinimidoacetic acid(7.0 g., 0.0416 mole) and phosphorus pentachloride (8.68 g., 0.0416mole) in a flask protected by a calcium chloride tube was allowed tofuse at room temperature. Benzene (50 ml.) was added and the mixture wasallowed to stand for ninety minutes at 30, followed by a thirty minuteperiod of heating under reflux. The filtered benzene solution wasconcentrated at 30 mm. and 50, thenrthree successive 25 ml. portions oftoluene were added and distilled. The oily residue of XVIII set to ahard, cream-colored solid on cooling, weight 7.1 g.

Recrystallization failed to improve the melting point, but conversion tothe corresponding anilide indicated a purity of not less than 76%. Theliterature value of the melting point is 76.

The anilide was prepared from 0.46 g. (0.0025 mole) of XVIII in 25 ml.of methylene chloride by addition of 0.465 g. (0.455 ml., 0.005 mole) ofaniline in methylene chloride at The yield of water-washed productwas.0.44 g. (76%), M. P. 151.5-152.5. tical sample was recrystallizedfrom acetone-cyclohexane, M. P. 152.5154.0.

Analysis.Calculated for C12H12N2Oz:

Calculated Found 0. 62. 06 n V 5. 21 N 12. 07

Calculated Found a 7 EXAMPLE XI2-phenyl-a-succinimido-2-thiazolidinoacetic acid ,8- lactam ()GO A. Highdilution in methylene chloride To a solution of 1.63 g. (0.01 mole) of2-phenyl-2- thiazoline (XIX) in 10 ml. of methylene chloride (dried overcalcium sulfate) in a 20.0-ml. three-necked flask was added 1.85 g.(0.01 'mole) of succinimidoacetyl chloride (XVIII) in 25 ml. ofmethylene chloride. To this rapidly stirred solution at reflux was addedthrough a high-dilution cycle a solution of 1.02 g. (0.01 mole) oftriethylamine in 50 ml. of methylene chloride over a six hour period.The resulting amber solution was concentrated to a brown magma, whichwas shaken with 50 ml. of benzene and filtered. The white crystallineresidue amounted to 1.50 g., or slightly more than the theoreticalamount of trimethylamine hydrochloride. The filtrate was concentrated toa brown oil which partially crystallized on standing several days underreducedpressure. The soft solid was triturated with ml. of 50% aqueousethanol and was stored overnight. On filtration, the crude lactam XX wasobtained as 1.70 g. (50%) of crisp, yellow needles, M. P. 148-160". A1.3 g. portion was taken up in 7 ml. of dioxane, ml. of water anddecolorized by boiling with Norit. On slow cooling, pure XX was obtainedas 0.600 g. of rectangular platelets, M. P. 166.0l68.5. An

An analy- V 16 analytical sample recrystallized from acetone-petroleumether melted at 1690-1700.

Analysis.Calculated for C15H14N2O3S:

Calculated Found C- 59. 58 59. 44 H 4. 67 4. 66 N 9. 27 9 B. Highdilution in benzene mole) of triethylamine' in 50 ml. of benzene-over afour-hour period. The precipitated triethylamine hydrochloride (3.43 g.,99%) was collected by filtration and the filtrate was concentrated atreduced pressure to a brown oil. On trituration of the residue withthree 30-ml. portions of ether, 5.87 g. of orange-yellow, crisp powderwas obtained in largely amorphous form, M. P. 140-155 A 1.0 g. portionof the powdery residue was extracted in a Soxhlet apparatus with 100 ml.of ether for fifteen hours. A crystalline fraction filtered from theextract amounted to 0.365 g. (28%) of crude lactam XX, M. P.155.5-160.0. The melting point of a portion recrystallized fromacetone-ether was 1600-1620".

On admixture with an authentic sample, the melting,

point was undepressed.

Partially purified XX could also be obtained from the crude reactionmixture by evaporative distillation. A 0.250 g. portion distilled at 15pressure and -160 yielded 0.050 g. (15.4% overall) of small prisms of)Q(, M. P. 155.0-1590".

EXAMPLE XII Sulfone of 2-phenyl-u-succinimido-Z-thiazolidineacetic acidS-lactam (XXIX) To a solution of 0.242 g. (0.0008 mole) of XX in 30 ml.of dioxane was added 0.34 g. of potassium permanganate in 3 ml. of waterand 10 ml. of acetic acid.

After forty minutes, the brown solution was decolorizedAnalysis.calculated for C15H14N2O5S1 Calculated Found C 53. 88 53.92 Fl4. 22 4. 41 r N 8. 38 8. 00

EXAMPLE XIII Z-phenyl-Z-(Z-carbomethoxypropionylamino)-2-thiozolidineacetic acid and 8-lactam (XXI) To a solution of 0.500 g.(0.00165 mole) of XX in 15 ml. of dioxane was added 17.0 ml. of 0.097 Nsodium hydroxide solution. After one hour, 15.9 ml. of 0.104 Nhydrochloric acid was added and the resulting solution was concentratedto dryness under reduced pressure. The organic portion of the residuewas taken up in 20 ml. of chloroform, and dried by shaking Withanhydrous magnesium sulfate for several minutes. To the filteredchloroform solution was added an excess (10 ml. of 0.32 N) ofdiazomethane in ether. After twenty minutes, several drops of aceticacid were added and the solution was concentrated to dryness underreduced pressure. The oil was dissolved in acetone and precipitated bythe addition of petroleum ether as 0.370 (67%) of colorless needles(XXI), M. P. 1095-1135. The crude product was dissolved in ml. ofdioxane and diluted with 5 ml. of cyclohexane. After removal of a traceof insoluble material, further dilution with 25 m1. of cyclohexaneyielded 0.230 g. (41.6%), M. P. 116.8- 117.8. An analytical sample ofXXI, M. P. 119.5- 120.5", was obtained on recrystallization first fromacetone-petroleum ether, and then from benzene-cyclohexane.

N (Z-hydroxy-Z-methyl propyl) -benzamide (XXIV) To 89.1 g. (1.0 mole) ofcommercial isobutanolamine in a H. round-bottomed flask was added 122.1g. (1.0 mole) of benzoic acid. After the initial exothermic reaction hadsubsided, the flask was immersed in an oil bath at 115 and heated to 135in twenty minutes. After two hours, the clear, yellow reaction mixturewas poured from the flask and allowed to crystallize to a hard cake.Recrystallization from benzene yielded XXIV as 146.6 g. (76%) of largecolorless plates, M. P. 103.5105.8". A portion recrystallized frombenzene for analysis melted at 105.5107.0.

Analysis-Calculated for C11H5NO22 Calculated An intimate mixture of145.0 g. (0.75 mole) of N-(2- hydroxy-2-methylpropyl)-benza.mide and63.7 g. (0.30 mole) of phosphorus pentasulfide was heated with a freeflame till fusion was complete and no further gas appeared to beevolved. The black fluid supernatant layer was decanted, and theresinous residue was leached with 180 ml. of N potassium hydroxidesolution and 60 ml. of ether over the course of one hour. The basiclayer was separated, and again extracted with three 25-ml. portions ofether. The combined ether layers were dried by twice decanting frompotassium hydroxide followed by potassium carbonate. The concentratedether extract and the original supernatant layer were combined anddistilled, B. P. 139 (4 mm.), n 1.5698, yield of XXV, 59.56 g. (41.2%).After redistillation the material had the following properties: n1.5708; B. P. 116 (2.4 mm.).

A picrate was prepared, M. P. 159.5-160.5.

Analysis.Calculated for C17H16N40'7S2 Calculated Found EXAMPLE XVI5,5-dimethyl-Z-phenyZ-a-succinimidO-Z-thiazolidineacetic acid it-lactam(XXVI) 18 high dilution cycle a solution of 1.02 g. (0.01 mole) oftriethylamine in 50 ml. of methylene chloride over a ten hour period.Concentration of the solution and extraction of the residue with 50 ml.of benzene yielded 1.67 g. (slightly more than the theoretical amount)of triethylamine hydrochloride. The filtrate was concentrated to aslowly crystallizing red oil, which yielded 0.89 g. (27%) of crude XXVI,M. P. -169", on trituration with three 10-1111. portions of 50% ethanol.Recrystallization from acetone-cyclohexane yielded 0.51 g. (15.5%) ofthe ,8- lactam XXVI, M. P. 181.0193.0. An analytical sample crystallizedfrom the same solvent pair melted at 1835-1840".

Analysis.-Calculated for C17H18N2O3S;

EXALIPLE XVII 5,5-dimethyI-Z-phenyl-a-phthalimido-Z-thiazoloa'ineaceticacid B-lactam (XXVII) To a rapidly stirred solution of 1.91 g. (0.01mole) of 5,5-dimethyl-2-thiazoline ()QiV) and 2.24 g. (0.01 mole) ofphthalimidoacetyl chloride in 50 ml. of ether at reflux was addedthrough a high dilution cycle 1.40 m. (1.02 g., 0.01 mole) oftriethylamine in 25 ml. of ether over a one and three-quarter hourperiod. The red solution was filtered and the collected tan solid, wt.2.49 g., was digested with two 20-m1. portions of water. The loss ofweight was 1.27 g., or 92.5% of the theoretical triethylarninehydrochloride. The residue, which amounted to 1.22 g., M. P. -213",yielded no fraction which could be identified as lactam and was notfurther examined.

The original ether filtrate after concentration crystallized in part onstanding, and after trituration with small portions of ether yielded0.480 g. (12.7%) of crude lactam fraction, M. P. 2000-2050. A 0.300 mg.portion was extracted with acetone and diluted with water, yielding0.120 g. (5%) of pure XXVII, M. P. 2150-2162. An analytical sampleobtained from acetone-water melted at 213.0215.0.

Analysis.-Calculated for C21H1sN2O3S:

EXAMPLE XVIII 4-ca1'b0meth0xy 5,5 dimethyl 2 phenyl asuccinimido-Z-thiaz0lidineacetic acid B-lactam (XXIX) To a solution of2.50 g. (0.01 mole) of 5,5-dimethyl-2- phenyl-2-thiazoline4-carboxylate,methyl ester (XXVIII) in 10 ml. of methylene chloride in a ZOO-ml.three-necked flask was added 25 ml. of methylene chloride and 1.85 g.(0.01 mole) of succinimidoacetyl chloride (XVIII). To this rapidlystirred solution at reflux was added through a high-dilution cycle asolution of 1.02 g. (0.01 mole) of triethylamine in 50 ml. of methylenechloride over a six and one-quarter hour period. The concentratedreaction mixture was extracted with 50 ml. of benzene in three portions.The combined residue, collected by filtration, amounted to 1.85 g. Theconcentrated benzene filtrate crystallized spontaneously on standing,and on tn'turation with 40 ml. of 50% ethanol-Water in two portionsyielded 0.510 g. (13.1%) of nearly pure lactam, M. P. 183.0- 184.5Recrystallization from acetone-cyclohexane containing a few drops ofacetic anhydride yielded the purified lactam XIGX, M. P. 186.8187.4,which apparently contained one-half mole of cyclohexane' ofcrystallization.

Analysis.Calculated for C15HzoN2O5S /2CGH12:

Calculated Found 7 EXAMPLE XIX. Sulfone of4-carbometh0xy-5,5-dimethyl-2-phenyl-a-succinimido-Z-lhiazolidineaceticacid ,B-lacta'm (XXX) 7 T o a solution of 0.194 g. (0.0005 mole) of thelactam (XXIX) in 15 ml. of dioxane was added 0.213 g. of potassiumpermanganate dissolved in 3 ml. of water and 8' Calculated Found C 54.32 54. 10 Fl 4. 79 4. 90 N 6. 67 6. 73

EXAIVIPLE XX Methyl -phenyl-(Z-carbomethoxyethyl) -penicillinate (X XXIA solution of 0.194 g. (0.0005 mole) of the lactam XXIX in 7 ml. ofanhydrous dioxane was titrated slowly to a phenolphthalein end pointwith 4.66 ml. (0.0005 mole) of 0.1074 N sodium hydroxide solution. Thesolution was neutralized with 4.84 ml. (0.0005 mole) of 0.1034 Nhydrochloric acid and then concentrated at 45 under reduced pressure.The residue was dissolved in ml. of chloroform and an excess ofdiazomethane in etherwas added. After fifteen minutes the excessdiazomethane was decomposed with acetic acid and the solution wasconcentrated to a yellow oil under reduced pres- Calculated Found C 57.13 57. 02 FT 5. 75 5. 68 N V 6. 66 6. 60

7 EXAMPLE xxr Degradation of the lactam XXIX A solution of 0.200 g. ofthe lactam XXIX in 10 ml. of N sodium hydroxide and 10 ml. of dioxanewas refluxed for two hours. The solvent mixture was distilled underreduced pressure and the yellow, oily residue taken up'in'20 ml..ofwater. The aqueous solution was acidified to pH 3 with 10 ml. of Nhydrochloric acid and then reconcentrated to dryness. The salts wereseparated by filtration of asolution of the residue in 10 ml. of

ethanol. The filtrate was treated with 0.400 g. of 2,4-dinitrophenyl-hydrazine dissolved in 2 ml. of concentrated sulfuric acidand 3 ml; of water. On dilution of the resulting solution with 8 ml. ofwater, an immediate precipitate-resulted, which was separated byfiltration after 30 minutes. The crystalline product amountedto 0.065 g.(30%), M. P. 179.2-181.6. A portion recrystallized from ethylacetate-carbon tetrachloride melted at Analysis.Calculated forC12H11N5O75 Calculated Found foa a -52.05 --51.9s H--. "-4.43 ----4;a6

'The melting point on admixture with an authentic synthetic sample ofXXXII, prepared as described below, was not depressed.

EXAMPLE XXII N-phenacylsuccinamic acid 2,4-dinitrophenylhydrazoneN-phenacylsuccinimide was prepared in 71% yield from succinimidoacetylchloride and benzene in the presence of aluminum chloride, M. P.(uncorr.) 143-144.

A suspension of 0.205 g. of N-phenacylsuccinimide in 2 ml. of N sodiumhydroxide was warmed a few minutes to effect complete solution. Afterseveral additional min- 7 utes at 85, the solution was diluted with 2m1. of water and acidified with 2.2 ml. of N hydrochloric acid. In aboutthirty seconds a voluminous mass of colorless crystals appeared(presumably N-phenacylsuccinamic acid). 7

The addition of 2 m1. of alcohol and reheatingthesuspension to 85 gave aclear solution, which was treated with a solution of 0.200 g. of2,4-dinitrophenylhydrazine in 1 ml. of sulfuric acid, 1.5 ml. of waterand 5 of ethanol. After one hour the crystalline precipitate wascollected by filtration and washed with 50% ethanol, weight 0.290 g.(66%); M. P. -186". Recrystallization from ethyl acetate-carbontetrachloride raised the M. P. to 1864-1873".

Analysis.-Calculated for C1aH1'zN5O7:

Calculated Found C 52. 05 51. 69 H 4. 13 4. 24 N 16. 86 16. 72

'Triethylamine is preferred but other basic tertiary amines may be usedprovided only that they be free of primary or secondary amines. Examplesare tripropylamine, trimethylamine, pyridine, quinoline andN,N-dimethylaniline.

Modifications may be made in carrying out the present inventionwithoutdeparting from the spirit or scope thereof, and the invention islimited only by the appended claims. 7 g

wherein R1 represents a member selected from the group consisting ofphthalimido, 3 -nitrophthalimido, succinimido, anddi-(methanesulfonyl)amino; R2 represents a member selected from thegroup consisting of hydrogen and phenyl; R3 and R4 each representa'member selected 2,72 1, 1 96 21 22 from the group consisting of loweralkyl and hydrogen and 7. The compound R3 and R4 are alike; and R5represents a member selected (CHJ), C CHCOOCH from the group consistingof hydrogen, carboxy and (lower) carbalkoxy. 2. The compound2-phenyl-a-phthalimido-2-thiazolidineacetic acid fi-lactam.

3. The compound 4. The compound 5. The compound i 6. The compound 8. Aprocess for the preparation of bicyclic fl-lactams which comprises theinteraction substantially in the range of 0 C. to C. of at least onemolecular equivalent of a basic tertiary amine bearing no functionalgroups, a halide selected from the group consisting of phthalylglycylchloride, B-nitrophthalylglycyl chloride, succinimidoacetyl chloride anddimethanesulfonylaminoacetyl chloride, and a Z-thiazoline in an amountsubstantially equivalent to the amount of halide used on a molecularbasis and having the formula R: C=N

wherein R2 represents a member selected from the group consisting ofhydrogen and phenyl; R3 and R4 each represent a member selected from thegroup consisting of lower alkyl and hydrogen and R3 and R4 are alike;and R5 represents a member selected from the group consisting ofhydrogen, carboxy and (lower) carbalkoxy.

9. A process according to claim 8 where the Z-thiazoline is2-phenyl-2-thiazoline.

10. A process according to claim 8 where the 2-thiazoline is methyl5,5-dimethyl-2-phenyl-2-thiazoline-4-carboxylate.

11. A process according to claim 8 where the halide is phthalylglycylchloride.

12. A process according to claim 8 where the halide is succinylglycylchloride.

13. A process according to claim'8 where the Z-thiazoline is methyl5,5-dimethyl-2-thiazoline-4-carboxylate.

14. A process according to claim 8 where the acyl halide isN,N-dimethanesulfonylglycyl chloride.

15. A process according to claim 9 where the basic tertiary amine istriethylamine.

16. A process according to claim 10 where the basic tertiary amine istriethylamine.

References Cited in the file of this patent UNITED STATES PATENTSBehrens et al Aug. 16, 1949 OTHER REFERENCES

1. A COMPOUND OF THE GENERAL FORMULA